Digital recording/playback apparatus with improved error correction capability of outer error correction coding and method therefor

ABSTRACT

A digital recording/playback apparatus with improved error correction capability and a method thereof are provided. In the apparatus and method thereof, regardless of trick play data and stuffing data, normal play data is outer-error-corrected. To enhance the error correction capability of the normal play data, during a recording mode, a predetermined pattern data is arranged in the stuffing data region and trick play data region and an outer parity is added to the normal play data to then be outer-error-correction coded. During a playback mode, the predetermined pattern data used during error-correction coding is arranged in the stuffing data region and trick play data region and inner-error-correction decoded normal play data is outer-error-correction decoded using the outer parity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to digital recording/playback, and moreparticularly, to error correction of a digital recording/playbackapparatus for recording/playing MPEG-2 (Moving Picture Experts Group)signals.

2. Description of the Related Art

A digital video apparatus can be applied to various fields such ascommunications, including teleconferencing and video phones, computers,or household electronic appliances. For example, a digitalrecording/playback apparatus such as a digital video cassette recorder(to be referred to as a D-VCR hereinafter) or a digital video cassette(DVC: to be also called a camcorder) adopts the MPEG-2 standard fordigital storage media.

According to the MPEG-2 standard, a program stream consists of therespective elementary streams for video, audio and user data, and ispacketized into a packetized elementary stream (PES).

Generally, a picture transmitted from a broadcast station consists of aPES, and one PES is transmitted in units of a predetermined number oftransport packets. Additionally, data on a transmission path is in asystem layer structure based on the MPEG-2 standard. The system layerstructure has a packet structure in units of 188 bytes. In each packet,a 4-byte header is divided into 1-byte sync and 3-byte side information.The number of bytes of the header can vary. The region of the packet,excluding the header, contains video data, audio data or user data.

When recording MPEG-2 bit streams, a digital recording/playbackapparatus extracts trick play data from the MPEG-2 bit streams as wellas normal play data to satisfy both a normal-play (NP) mode and atrick-play (TP) mode, and records the extracted trick play data on aseparate trick play data region.

Also, a digital recording/playback apparatus can record an ATV (AdvancedTelevision) signal which is an American type of HDTV (High DefinitionTelevision) signal, or a DVB (Digital Video Broadcasting) signal whichis an European type of HDTV signal, both of which adopt MPEG-2compression. The digital recording/playback apparatus records the signalin a 25, 12.5 or 6.25 Mbps recording mode according to the bit rate of atransmitted signal. If there is a difference between the bit rate of arecording mode and that of the transmitted signal, a stuffing region isallocated to a predetermined region of the normal play data region,thereby recording stuffing data, i.e., dummy data. In performing errorcorrection coding and decoding in consideration of the stuffing data,the capability of correcting errors of normal play data is affected bythe quantity of the stuffing data. The present invention has beenproposed to improve the capability of correcting errors of normal playdata, without being affected by the stuffing data which is the dummydata.

Also, when the video bit stream of an MPEG-2 format is recorded by thedigital recording/playback apparatus, an ECC (Error Correction Code)structure of a track format is for recording inter-picture coded bitstreams. Thus, the inter-picture coded bit streams such as the ATV orDVB signal are susceptible to error.

To solve the problem, a predetermined region of the normal play dataregion is allocated, called an ECC3 region, for storing outer parity forcorrecting errors of only the normal play data.

However, in performing error correction coding using the additionallyprovided ECC3 region, the normal play data of the ECC structure iswritten in units of a predetermined number (10 typically) tracks and theouter parity is added to the ECC3 region to allow interleaving tocorrect burst errors. This requires a large capacity memory. Inpractice, decoding the ECC3 requires complicated hardware.

SUMMARY OF THE INVENTION

To solve the above problems, it is a first objective of the presentinvention to provide a digital recording/playback apparatus forperforming outer error correction coding by arranging a predeterminedpattern data in a stuffing region and a trick play data region for anECC block containing the stuffing region, during a recording mode, andperforming outer error correction decoding by arranging the pattern dataused in the coding is in the stuffing region and the trick play dataregion, during a playback mode.

It is a second objective of the present invention to provide a digitalrecording/playback apparatus for performing outer error correctioncoding by arranging a predetermined pattern data in an ECC3 regionadditionally provided in the normal play data region, during a recordingmode, and performing outer error correction decoding by arranging thepattern data used in the coding in the ECC3 region, during a playbackmode.

It is a third objective of the present invention to provide a digitalrecording/playback method for performing outer error correction codingby arranging a predetermined pattern data in a stuffing region and atrick play data region for an ECC block containing the stuffing region,during a recording mode, and performing outer error correction decodingby arranging the pattern data used in the coding in the stuffing regionand the trick play data region, during a playback mode.

It is a fourth objective of the present invention to provide a digitalrecording/playback method for performing outer error correction codingby arranging a predetermined pattern data in an ECC3 region additionallyprovided in the normal play data region, during a recording mode, andperforming outer error correction decoding by arranging the pattern dataused in the coding in the ECC3 region, during a playback mode.

Accordingly, to achieve the first objective, there is provided a digitalrecording/playback apparatus for recording normal play data and trickplay data separately on a recording medium in a predetermined dataformat, and reproducing the data recorded on the recording medium, theapparatus comprising: an adding unit for adding extra informationindicative of a decoding timing to a received transport stream andoutputting the normal play data in units of a predetermined number ofsync blocks; an extracting unit for extracting the trick play data fromthe received transport stream and outputting the trick play data inunits of a predetermined number of sync blocks; an arranging unit forarranging the normal play data in a normal play data region, the trickplay data in a trick play data region, and predetermined patternstuffing data in a stuffing region of the normal play data regionaccording to a difference between a predetermined recording rate and abit rate of the transport stream; an error correction coder forperforming outer error correction on the normal play data, regardless ofthe trick play data and stuffing data among the arranged data, andoutputting error-correction-coded data; and a modulator for modulatingthe error-correction-coded data and transmitting modulated data to therecording medium.

Here, the error correction coder comprises: an outer error correctioncoder for arranging a predetermined pattern data in the stuffing regionand the trick play data region, adding an outer parity to the normalplay data, and outputting outer-error-correction-coded data; and aninner error correction coder for adding an inner parity to theouter-error-correction-coded data output from the outer error correctioncoder, and outputting inner-error-correction-coded data.

Also, the digital recording/playback apparatus further comprises: ademodulator for demodulating the data recorded on the recording mediumand outputting demodulated data; an error correction decoder forperforming error-correction-decoding on the demodulated data; and aselector for selecting error-correction decoded normal play data duringa normal play mode, and selecting error-correction decoded trick playdata during a trick play mode, according to a normal/trick play modesignal, wherein the error correction decoder comprises: an inner errorcorrection decoder for performing inner error correction decoding on thedemodulated normal play data using the inner parity during a normal playmode and outputting inner-error-correction-decoded normal play data tothe selector, and for performing inner error correction decoding on thedemodulated trick play data using the inner parity during a trick playmode and outputting inner-error-correction-decoded trick play data tothe selector; and an outer error correction decoder for arranging thepredetermined pattern data used in the error correction coding in thestuffing region and the trick play data region, performing outer errorcorrection decoding on the inner-error-correction-decoded normal playdata using the outer parity, and outputtingouter-error-correction-decoded data.

To achieve the second objective, there is provided a digitalrecording/playback apparatus wherein an outer error correction coderperforms outer error correction coding by overwriting the predeterminedpattern data in a separate error correction code region of the normalplay data region, and an outer error correction decoder performs outererror correction decoding by overwriting the predetermined pattern datain a separate error correction code region of the normal play dataregion.

To achieve the third objective, there is provided a method for recordingnormal play data and trick play data separately on a recording medium ina predetermined data format, and reproducing the data recorded on therecording medium, comprising the steps of: (a) adding extra informationindicative of a decoding timing to a received transport stream andoutputting a transport packet to which the extra information is added;(b) mapping a first predetermined number of transport packets, to whichthe extra information is added, in units of a second predeterminednumber of sync blocks and outputting the normal play data; (c)extracting trick play data from the received transport stream; (d)packetizing extracted trick play data, mapping the first predeterminednumber of transport packets of packetized trick play data in units ofthe second predetermined number of sync blocks and outputting the trickplay data; (e) arranging the normal play data in a normal play dataregion, the trick play data in a trick play data region, andpredetermined pattern stuffing data in a stuffing region of the normalplay data region according to a difference between a predeterminedrecording rate and a bit rate of the transport stream; (f) performingouter error correction on the normal play data, regardless of the trickplay data and stuffing data among the arranged data, and outputtingerror-correction-coded data; and (g) modulating theerror-correction-coded data and transmitting modulated data to therecording medium.

Here, the step (f) comprises the steps of: (f1) arranging apredetermined pattern data in the stuffing region and the trick playdata region, adding an outer parity to the normal play data, andoutputting outer-error-correction-coded data; and (f2) adding an innerparity to the outer-error-correction-coded data, and outputtinginner-error-correction-coded data.

Also, the method further comprises the steps of: (h) demodulating thedata recorded on the recording medium and outputting demodulated data;(i) performing error-correction-decoding on the demodulated data; and(j) selecting error-correction decoded normal play data during a normalplay mode, and selecting error-correction decoded trick play data duringa trick play mode, according to a normal/trick play mode signal, whereinthe step (i) comprises the steps of:

(i1) performing inner error correction decoding on the demodulatednormal play data using the inner parity during a normal play mode andoutputting inner-error-correction-decoded normal play data, andperforming inner error correction decoding on the demodulated trick playdata using the inner parity during a trick play mode and outputtinginner-error-correction-decoded trick play data; and

(i2) arranging the predetermined pattern data used in the errorcorrection coding in the stuffing region and the trick play data region,performing outer error correction decoding on theinner-error-correction-decoded normal play data using the outer parity,and outputting outer-error-correction-decoded data.

To achieve the fourth objective, according to the present invention, inthe step (i2), outer error correction decoding is performed byoverwriting the predetermined pattern data used during the errorcorrection coding in a separate error correction code region of thenormal play data region.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objectives and advantages of the present invention will becomemore apparent by describing in detail a preferred embodiment thereofwith reference to the attached drawings in which:

FIG. 1 is a block diagram of a coder for a digital video cassetterecorder according to an embodiment of the present invention;

FIG. 2 is an example of a track format of a signal supplied forrecording on a digital video tape;

FIG. 3 shows a format of an ECC block recorded on a video sector shownin FIG. 2;

FIG. 4 is a table for explaining a sync block extra header shown in FIG.3;

FIGS. 5A and 5B illustrate 2-to-5 mapping performed in a buffercontroller shown in FIG. 1, and a time stamp shown in FIG. 5A,respectively;

FIG. 6 illustrates outer error correction coding performed in an outererror correction coder shown in FIG. 1; and

FIG. 7 is a block diagram of a decoder for the digital video cassetterecorder according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of a digital recording/playback apparatus andmethod according to the present invention will now be described withreference to the accompanying drawings.

In FIG.1, a program selector 102 selects a transport stream of a programcorresponding to the program number input by a user from an MPEG-2transport stream, outputs the transport stream of the selected programto a time stamp adder 108, outputs a PCR (Program Clock Reference)extracted from the transport stream to a PLL (Phase Locked Loop) circuit104, and outputs a video layer extracted from the transport stream to anI (Intra)-picture extractor 114. The PLL circuit 104 generates a 27 MHZclock signal synchronized with a 27 MHZ clock signal used during thetransmission, based on the PCR output from the program selector 102.

Here, the video image is digitized and made into a bit stream in anMPEG-2 structure to be transmitted as compressed data. The bit stream isconstructed of a video layer structure and a transport layer structure.A signal subjected to MPEG-2 compression is added to the video layerstructure, and a header for transmission is added to the transportlayer, so that the data is transmitted in units of transport packets.

A timing & control signal generator 106 up-counts the 27 MHZ clocksignal generated in the PLL circuit 104, applies the counted value tothe time stamp adder 108, applies a track signal indicative of a trackon a tape to a buffer controller 112 and a RAM controller 122, applies aregion control signal indicative of whether the pertinent region is anormal play data region, stuffing region, ECC3 region or trick play dataregion, to a multiplexer (MUX) 126, and applies an ECC block signalindicative of an ECC block to an error correction coder 128.

The time stamp adder 108 adds a time stamp indicative of the time forthe transport stream to arrive in the coder, to each transport packetoutput from the program selector 102, in order to restore the transportstream in the same time interval in the decoder of the digital VCR.

A first buffer 110 temporarily stores the normal play data with the timestamp added thereto, output from the time stamp adder 108. The buffercontroller 112 includes a 2-to-5 mapper for separating a 1-byte syncfrom the normal play data (NP_data) of the 188 byte transport packet,temporarily stored in the first buffer 110, collecting two 187-bytepackets and mapping the same into five sync blocks.

The buffer controller 112 reads the normal play data in units of 5 syncblocks according to a track signal generated in the timing & controlsignal generator 106 to correspond with the normal play data region ofthe ECC block, and generates predetermined pattern data (pattern data)for the stuffing data region and ECC3 region of the normal play dataregion. The stuffing data region is preferably constructed in units of 5sync blocks. 10 sync blocks are allocated to the ECC3 region.

As described above, recording is performed at rates of 25, 12.5 or 6.25Mbps recording mode according to the bit, rate of the ATV or DVB signalrecorded in the digital VCR. If the bit rate of an input source bitstream, i.e., an input MPEG-2 bit stream, is 13 Mbps, the bit streammust be recorded and reproduced in the 25 Mbps recording mode. Thestuffing data of a predetermined pattern is stuffed in the portionhaving a difference between the bit rate of the transmitted signal andthat of the recording mode. The greater the difference, the morestuffing data is stuffed therein.

Here, the data of a predetermined pattern is in units of bytes, thestuffing data of a predetermined pattern is an 8-bit binary value, andcan be set from “00000000” to “11111111”. Preferably, an arithmetic zeropattern is used. Since the arithmetic zero pattern is easy to generate,a read-only memory (ROM) is not necessary for storage of data patterns.Moreover, since additions may be omitted from calculations concerningthe arithmetic zero, the arithmetic zero pattern simplifies thecalculation for outer error correction, like in the coding process andthe decoding process for reproducing the recorded video signal.

FIG. 2 is an example of a track format of an ATV or DVB signal suppliedfor recording on a digital video tape. As shown in FIG. 2, the format ofthe signal read from a head of the D-VCR is constructed such that eachtrack consists of an ITI (Insert and Track Information) sector, an audiosector, a video sector and a subcode sector, sequentially arranged fromthe track start part at which the head starts scanning.

Also, during the playback mode of the D-VCR, if the head deviates fromthe track of a magnetic tape, the outputs of the head decrease and theerrors increase, which makes it difficult to achieve normal play of theD-VCR. Thus, different pilot signals are recorded on consecutive tracks,e.g., in a F0-F1-F0-F2 pattern sequence, and the crosstalk of the pilotsignals of the preceding and following tracks of a track that the headtraces most closely are compared. Then, it is detected how the headtracking deviates from the pertinent track relative to the precedingtrack or the following track, so that the head can trace a target trackexactly. In the video region of the video sector, every second trackcontains six trick play data regions, in which high speed trick playdata are recorded, and every fourth track contains one trick play dataregion in which low speed trick play data are recorded. In FIG. 2, thetrick play data regions are shaded. In the remaining video region, thenormal play data or stuffing data is recorded. The high and low speedtrick play data regions may be differently arranged according to amultiple times speed mode, and are allocated in units of 5 sync blocksor a multiple thereof.

The video sector of the track format shown in FIG. 2 has an ECCstructure, as shown in FIG. 3. In FIG. 3, the video sector consists ofsync blocks 19 and 20 as a first video auxiliary region (VAUX), syncblocks 21-155 as a video data region, sync block 156 as a second videoauxiliary data region, and sync blocks 157-167 as an outer parityregion. Each sync block has a 2-byte sync code, a 3-byte ID, 77 bytes ofdata and an 8-byte inner parity for inner error correction. An ECC2region is a region to which outer codes are added for storage of outerparity information in an ECC structure, and an ECC1 region is a regionto which inner codes are added for storage of inner parity informationin the ECC structure.

Video auxiliary data such as a program number input by a user andsupplied from a servo mechanism system controller (not shown) is writtenin the first and second video auxiliary data regions.

In the video data region of sync blocks 21-55, there is an ECC3 region(sync blocks 21-30), a normal play data region and a trick play dataregion, as shown in FIG. 2, the normal play data region containing astuffing region.

Each of sync blocks (77 bytes) 21-155 of the video data region has a1-byte sync block extra header (SB_EXTRA_HEADER). The sync block extraheader (SB_EXTRA_HEADER) is a header for indicating whether the data ofthe sync block is the normal play data, trick play data, stuffing dataor ECC3 data.

A table for explaining the content of the sync block extra header(SB_EXTRA_HEADER) is shown in FIG. 4. In FIG. 4, in the sync block extraheader (SB_EXTRA_HEADER) of sync blocks 31-155, if the most significantbit b7 (MSB) is “0” and the second most significant bit b6 is also “0”,then the data of sync block is stuffing data. If the MSB b7 is “0” andthe second most significant bit b6 is “1”, the data of the sync block isnormal play data. If the MSB is “1”, then the data of the sync block istrick play data, and the second most significant bit is a toggle bitindicative of the pertinent packet of two packets, and the next fivelower bits are the sync block ID of the trick play data.

In the sync block extra header (SB_EXTRA_HEADER) of sync blocks 21-30,if the MSB is “0”, then the data region of the sync block is an ECC3region. A predetermined pattern data is written on the ECC3 regionaccording to the present invention.

FIG. 5A illustrates 2-to-5 mapping performed in a buffer controller 112shown in FIG. 1. The 2-to-5 mapping refers to mapping two transportpackets into 5 sync blocks. A 3-byte time stamp indicative of a decodingtiming is added to each packet, and a 1-byte sync block extra header isadded to each sync block. Here, although a D-VCR or DVC system forrecording the DVB or ATV signal generally performs 2-to-5 mapping, aDVHS (Digital Video Home System) may perform 2-to-3 mapping. Thus, thepresent invention is not limited to the 2-to-5 mapping.

FIG. 5B illustrates the internal structure of a 3-byte time stamp shownin FIG. 5A. The time stamp shown in FIG. 5B has a first time stampregion (TSH) and a second time stamp region (TSL). The second stampregion (TSL), comprised of 18 lower significant bits, stores the countedvalues counted by the 27 MHZ clock signal within 2 tracks. The firststamp region (TSH), comprised of the next 3 upper bits of the secondstamp region (TSL), stores the counted values corresponding to 16tracks, since the counted values increasing in units of 2 tracks arestored.

Since the D-VCR is operable in a track playback mode, trick play datamust be extracted. The MPEG-2 bit stream is subjected to MPEG-2compression, the quantities of compressed data are different for eachpicture, thereby disabling trick play implementation by the normal playdata. Thus, the I-picture extractor 114 extracts I-picture data from avideo layer output from the program selector 102.

The second buffer 116 temporarily stores the extracted I-picture data, aVLD analyzer 118 performs VLD (Variable Length Decoding) on theI-picture data stored in the second buffer 116 and extracts the trickplay data having a DC coefficient and a predetermined number of lowfrequency AC coefficients on a DCT block. The packetizer & mapper 120packetizes the extracted trick play data in the form of 188-bytetransport packet by adding the transport packet header thereto,separates a 1-byte sync from the packetized trick play data, collectstwo 187-byte packets, maps the same into 5 sync blocks, adds the timestamp to each packet and adds the sync block extra header(SB_EXTRA_HEADER) as shown in FIGS. 3 and 4 to each sync block. Here,the time stamp for trick play data does not contain informationindicative of a decoding timing, unlike the time stamp for normal playdata.

The RAM controller 122 writes the trick play data (TP_data) output fromthe packetizer & mapper 120 in units of 5 sync blocks in the RAM 124,and reads the trick play data stored in the RAM 124 to be recorded onthe trick play data region of a predetermined track according to a tracksignal generated in the timing & control signal generator 106. In thiscase, since the trick play data may be repeatedly written on the trickplay data region according to a multiple times speed mode, the RAM 124is necessary.

According to a region control signal generated in the timing & controlsignal generator 106, a multiplexer 126 selects the normal play data(NP-data) read from the buffer controller 112 in the normal play dataregion of the ECC block, selects the predetermined pattern data (patterndata) which is arithmetic zero, output from the buffer controller 112 inthe stuffing region and the ECC region, and selects the trick play dataof the RAM 124 in a predetermined trick play data region of a track. Thetrick play data is both high speed trick play data for the high speeddata region and low speed trick play data for the low speed data region,shown in FIG. 2.

An error correction coder 128 arranges the normal play data and trickplay data selected by the multiplexer 126 according to an ECC blocksignal generated in the timing & control signal generator 106, and thenperforms outer and inner error correction coding. Here, at least one ECCblock is allocated to each track. In detail, the error correction coder128 includes an outer error correction coder 130, a first memory 132, aninner error correction coder 134, and a second memory 136.

The error correction coder 128 adds an 11-byte outer parity to a138-byte outer code in a row direction to then perform outer errorcorrection coding, and then adds an 8-byte inner parity to a 77-byteinner code in a column direction, during a recording mode. The ECC3region remains as an optional region, without an outer parity for normalplay data error correction added thereto. The central concept of thepresent invention is to enhance the error correcting capability for thenormal play data in performing the outer error correction coding,regardless of error correction coding for the stuffing data.

In other words, as shown in FIG. 6, the outer error correction coder 130arranges the predetermined pattern data (here, arithmetic zero, i.e.,“0000”) in the ECC3 region, stuffing region and trick play data regionand adds an 11-byte outer parity to 138 bytes in the ECC2 region. Thus,during the outer error correction coding, the data of the ECC3, stuffingand trick play data regions are disregarded, and the outer parity isadded to only the normal play data, thereby improving the errorcorrection capability for the normal play data. Here, the first memory132 has a memory size of at most one field to be used during the outererror correction coding.

The inner error correction coder 134 adds an 8-byte inner parity to each77-byte sync block of the outer-error-correction-coded data output fromthe outer error correction coder 130 in the ECC1 region. The secondmemory 136 has a memory size of at least one sync block to be usedduring the inner error correction coding.

In addition, the 2-byte sync data and 3-byte ID data shown in FIG. 3 maybe added either before the outer error correction coding or after theinner error correction coding.

A modulator 138 performs 24-to-25 modulation on theerror-correction-coded data output from the error correction coder 128in a known manner. Alternatively, interleaving may be performed beforemodulation, to give protection against burst errors. The specific datamodulating scheme used during recording is not relevant in the presentinvention.

FIG. 7 shows a decoder for the D-VCR for reproducing the data recordedon a digital video tape.

In FIG. 7, a demodulator 202 demodulates data read from a digital videotape (T) in accordance with the modulating scheme used during recording.Here, a 2-byte sync and a 3-byte ID can be separated from thedemodulated normal play data and trick play data. Otherwise, the230-byte sync and the 3-byte ID can be separated after outer errorcorrection decoding.

An error correction decoder 204 performs inner error correction decodingin a row direction, that is, error correction is performed up to 4 bytesamong 85 bytes, and then an error flag is added to uncorrected syncblocks.

Here, during the outer error correction decoding, the uncorrected syncblocks are corrected using the error flag representing the sync blocksto be subjected to error correction, and the error correction isperformed in a column direction, up to 11 bytes among 149 bytes. Theerror correction decoder 204 includes an inner error correction decoder206, a first memory 208, a sync block extra header analyzer 210, anouter error correction decoder 212 and a second memory 214.

The inner error correction decoder 206 performs inner error correctioncoding on the normal play data sync block, trick play data sync block,stuffing data sync block, and ECC3 region sync block, using the innerparity. The first memory 208 which is used in the inner error correctiondecoding has a memory size of at least one sync block.

The sync block extra header analyzer 210 analyzes the sync block extraheader added to the inner-error-correction-coded data to determinewhether the inner-error-correction-coded data is the data of the normalplay data region, trick play data region, stuffing data region or ECC3region.

If the pertinent data is determined to be in the normal play dataregion, trick play data region, stuffing data region or ECC3 regionaccording to the sync block extra header, then the outer errorcorrection decoder 212 arranges the predetermined pattern data used incoding, and performs outer error correction decoding. The second memory214 has a memory size of an ECC block to be used in outer errorcorrection decoding, i.e., at most one track.

During a normal play mode, the outer error correction decoder 212performs the outer error correction decoding in the following manner.For the 21st through 30th sync blocks, if the MSB of the sync blockextra header analyzed in the sync block extra header analyzer 210 is“0”l, the sync blocks are determined to be in the ECC3 region. Thus, thepredetermined pattern data (here, arithmetic zero) is overwritten on 76sync blocks excluding the sync block extra header, in the ECC3 region.For the 31st through 155th sync blocks, if the MSB of the sync blockextra header analyzed in the sync block extra header analyzer 210 is“1”, the sync blocks are determined to be in the trick play data region.Thus, the predetermined pattern data (here, arithmetic zero) isoverwritten on the 76 sync blocks excluding the sync block extra header,in the trick play data region. Otherwise, if both the MSB and the secondmost significant bit of the sync block extra header analyzed in the syncblock extra header analyzer 210 are “0”, the sync blocks are determinedto be in the stuffing region. Thus, the stuffing data used in the coding(here, arithmetic zero) is overwritten on 76 sync blocks excluding thesync block extra header.

Thus, a probable channel error in the ECC3 region, trick play dataregion and stuffing region is negligible, thereby improving the errorcorrection capability for the normal play data. The error correctionmethod according to the present invention can greatly improve the errorcorrection capability for the normal play data, as the differencebetween the recording mode bit rate and the actually recorded bit rateis relatively greater.

A demultiplexer (DEMUX) 216 outputs data to different paths for thenormal play data or the trick play data depending on a normal play ortrick play mode signal (NP/TP mode).

The normal play data is output to a buffer 218, a restoration timecontroller 220, an oscillator 222 and a timing generator 224, during anormal play mode. Here, the oscillator 222 and the timing generator 224may be incorporated into the PLL circuit 104 and the timing & controlsignal generator 106 respectively, of the coder shown in FIG. 1.

During a normal play mode, the outer-error-correction-decoded normalplay data output from the outer error correction decoder 212 through thedemultiplexer 216 is read out for each sync block and temporarily storedin the buffer 218 in units of five 77-byte sync blocks. The restorationtime controller 220 separates the time stamp from the normal data storedin the buffer 218 to form the separated time stamp into two 187-bytetransport packets. Then, a 1-byte packet sync is added to the respectivepackets to form two 188-byte transport packets, so that the transportpackets packetized according to the time stamp, that is, according tothe time at which the normal play data was input to the coder, areoutput through a multiplexer 230.

Here, the timing generator 224 up-counts according to a clock signal ofthe 27 MHZ frequency generated by the oscillator 222 and outputs thecounted value to the restoration time controller 220. In other words,the restoration time controller 220 compares the counted value outputfrom the timing generator 224 with the time stamp for the transportpacket of the normal play data, and outputs the compared data accordingto the comparison result.

Trick play data is output to a RAM controller 226 and a RAM 228. Inother words, during a trick play mode, theinner-error-correction-decoded trick play data output from the innererror correction decoder 206 through the demultiplexer (DEMUX) 216 iswritten to the RAM 228 and then output according to the control of theRAM controller 226. The RAM controller 226 removes overlapping data ornon-trick play data among the trick play data scanned when the trickplay data region of the tape for a trick play mode is scanned. Also, theRAM controller 226 rearranges sync blocks during a backward search modeand writes the same to the RAM 228. The overlapping data can begenerated by repeatedly writing the trick play data to tracks accordingto a multiple times speed function. Also, the non-trick play multipletimes speed data corresponding to the trick play speed selected by auser may be read by the head during the trick play mode.

Also, the RAM controller 226 reads the rearrangedinner-error-correction-decoded trick play data from the RAM 228 to formunits of two 187-byte transport packets, and adds a 1-byte packet syncto each packet to then output 188-byte transport packets through themultiplexer (MUX) 230.

According to a normal play/trick play mode signal (NP/TP mode), themultiplexer 230 outputs the output of the restoration time controller220 during a normal play mode, and outputs the output of the RAMcontroller 226 during a trick play mode.

As described above, according to the present invention, predeterminedpattern data is arranged in an ECC3 region, a stuffing region and atrick play data region and then outer-error-correction coded during arecording, and the predetermined pattern data used in coding arerearranged in the respective regions and then outer-error-correctiondecoded during a playback. Thus, errors generated in the ECC3 region,the stuffing region and the trick play data region are negligible, andonly the normal play data is error-corrected, thereby enhancing theerror correction capability. Also, the more the stuffing data, thegreater the error correction capability.

What is claimed is:
 1. A digital recording/playback apparatus forrecording normal play data and trick play data separately on a recordingmedium in a predetermined data format, and reproducing the data recordedon the recording medium, the apparatus comprising: an adding unit foradding extra information indicative of a decoding timing to a receivedtransport stream and outputting the normal play data in units of apredetermined number of sync blocks; an extracting unit for extractingthe trick play data from the received transport stream and outputtingthe trick play data in units of a predetermined number of sync blocks;an arranging unit for arranging the normal play data in a normal playdata region, the trick play data in a trick play data region, and apredetermined pattern data in a stuffing region of the normal play dataregion according to a difference between a predetermined recording rateand a bit rate of the transport stream; an error correction coder forperforming outer error correction on the normal play data, regardless ofthe trick play data and stuffing data among the arranged data, andoutputting error-correction-coded data; and a modulator for modulatingthe error-correction-coded data and transmitting modulated data to therecording medium, wherein the error correction coder comprises: an outererror correction coder for arranging the predetermined pattern data inthe stuffing region and the trick play data region simultaneously,adding an outer parity to the normal play data, and outputtingouter-error-correction-coded data of normal play data; and an innererror correction coder for adding an inner parity to theouter-error-correction-coded data output from the outer error correctioncoder, and outputting inner-error-correction-coded data.
 2. The digitalrecording/playback apparatus according to claim 1, wherein the errorcorrection coder further comprises: a first memory having a memory sizeto accommodate a predetermined data format to be used during outer errorcorrection coding; and a second memory having a memory size toaccommodate at least one sync block to be used during inner errorcorrection coding.
 3. The digital recording/playback apparatus accordingto claim 2, wherein each byte of the predetermined pattern data is apredetermined number.
 4. The digital recording/playback apparatusaccording to claim 3, wherein each number in the predetermined patterndata is the same as the other numbers in the predetermined pattern. 5.The digital recording/playback apparatus according to claim 4, whereinthe predetermined pattern data corresponds to arithmetic zero.
 6. Adigital recording/playback apparatus for recording normal play data andtrick play data separately on a recording medium in a predetermined dataformat, and reproducing the data recorded on the recording medium, theapparatus comprising: an adding unit for adding extra informationindicative of a decoding timing to a received transport stream andoutputting the normal play data in units of a predetermined number ofsync blocks; an extracting unit for extracting the trick play data fromthe received transport stream and outputting the trick play data inunits of a predetermined number of sync blocks; an arranging unit forarranging the normal play data in a normal play data region, the trickplay data in a trick play data region, and a predetermined pattern datain a stuffing region of the normal play data region according to adifference between a predetermined recording rate and a bit rate of thetransport stream; an error correction coder for performing outer errorcorrection on the normal play data, regardless of the trick play dataand stuffing data among the arranged data, and outputtingerror-correction-coded data; and a modulator for modulating theerror-correction-coded data and transmitting modulated data to therecording medium, wherein the error correction coder comprises: an outererror correction coder for arranging the predetermined pattern data inthe stuffing region and the trick play data region simultaneously,adding an outer parity to the normal play data, and outputtingouter-error-correction-coded data of normal play data; and an innererror correction coder for adding an inner parity to theouter-error-correction-coded data output from the outer error correctioncoder, and outputting inner-error-correction-coded data, wherein theouter error correction coder performs outer error correction coding byoverwriting the predetermined pattern data in a separate errorcorrection code region of the normal play data region, said separateerror correction code region being provided as part of the normal playdata region in addition to said stuffing region and trick play dataregion.
 7. The digital recording/playback apparatus according to claim6, wherein each byte of the predetermined pattern data is apredetermined number.
 8. The digital recording/playback apparatusaccording to claim 7, wherein each number in the predetermined patterndata is the same as the other numbers in the predetermined pattern. 9.The digital recording/playback apparatus according to claim 8, whereinthe predetermined pattern data corresponds to arithmetic zero.
 10. Adigital recording/playback apparatus for recording normal play data andtrick play data separately on a recording medium in a predetermined dataformat, and reproducing the data recorded on the recording medium, theapparatus comprising: an adding unit for adding extra informationindicative of a decoding timing to a received transport stream andoutputting the normal play data in units of a predetermined number ofsync blocks; an extracting unit for extracting the trick play data fromthe received transport stream and outputting the trick play data inunits of a predetermined number of sync blocks; an arranging unit forarranging the normal play data in a normal play data region, the trickplay data in a trick play data region, and a predetermined pattern datain a stuffing region of the normal play data region according to adifference between a predetermined recording rate and a bit rate of thetransport stream; an error correction coder for performing outer errorcorrection on the normal play data, regardless of the trick play dataand stuffing data among the arranged data, and outputtingerror-correction-coded data; and a modulator for modulating theerror-correction-coded data and transmitting modulated data to therecording medium, wherein the error correction coder comprises: an outererror correction coder for arranging the predetermined pattern data inthe stuffing region and the trick play data region simultaneously,adding an outer parity to the normal play data, and outputtingouter-error-correction-coded data of normal play data; and an innererror correction coder for adding an inner parity to theouter-error-correction-coded data output from the outer error correctioncoder, and outputting inner-error-correction-coded data, furthercomprising: a demodulator for demodulating the data recorded on therecording medium and outputting demodulated data; an error correctiondecoder for performing error-correction-decoding on the demodulateddata; and a selector for selecting error-correction decoded normal playdata during a normal play mode, and selecting error-correction decodedtrick play data during a trick play mode, according to a normal/trickplay mode signal, wherein the error correction decoder comprises: aninner error correction decoder for performing inner error correctiondecoding on the demodulated normal play data using the inner parityduring a normal play mode and outputting inner-error-correction-decodednormal play data to the selector, and for performing inner errorcorrection decoding on the demodulated trick play data using the innerparity during a trick play mode and outputtinginner-error-correction-decoded trick play data to the selector; and anouter error correction decoder for arranging the predetermined patterndata used in the error correction coding in the stuffing region and thetrick play data region, performing outer error correction decoding onthe inner-error-correction-decoded normal play data using the outerparity, and outputting outer-error-correction-decoded data.
 11. Thedigital recording/playback apparatus according to claim 10, wherein theouter error correction decoder performs outer error correction decodingby overwriting the predetermined pattern data in a separate errorcorrection code region of the normal play data region, said separateerror correction code region being provided as part of the normal playdata region in addition to said stuffing region and trick play dataregion.
 12. The digital recording/playback apparatus according to claim10, wherein the error correction decoder further comprises: a firstmemory having a memory size to accommodate at least one sync block to beused during inner error correction decoding; an extra header analyzerfor analyzing a sync block extra header added to theinner-error-correction-decoded data and outputting the analyzedinformation to the outer error correction decoder; and a second memoryhaving a memory size to accommodate the predetermined data format to beused during outer error correction decoding.
 13. The digitalrecording/playback apparatus according to claim 10, further comprising:a demultiplexer for outputting the outer-error-correction-decoded normalplay data during the normal play mode and outputting aouter-error-correction-decoded trick play data during the trick playmode, according to a normal/trick play mode signal; a buffer fortemporarily storing the outer-error-correction-decoded normal play dataoutput from the demultiplexer; a restoration time controller forpacketizing the normal play data read from the buffer into a transportpacket, and outputting the normal play data based on a time stamp addedto the transport packet; a RAM for writing and reading theinner-error-correction-decoded trick play data output through thedemultiplexer; and a RAM controller for rearranging the trick play dataafter removing overlapping data and normal play data from the trick playdata, writing rearranged trick play data to the RAM,transport-packetizing the trick play data in the RAM and outputtingpacketized trick play data to a second selector.
 14. A method forrecording normal play data and trick play data separately on a recordingmedium in a predetermined data format, and reproducing the data recordedon the recording medium, the method comprising the steps of: (a) addingextra information indicative of a decoding timing to a receivedtransport stream and outputting a transport packet to which the extrainformation is added; (b) mapping a first predetermined number oftransport packets, to which the extra information is added, in units ofa second predetermined number of sync blocks and outputting the normalplay data; (c) extracting trick play data from the received transportstream; (d) packetizing extracted trick play data, mapping the firstpredetermined number of transport packets of packetized trick play datain units of the second predetermined number of sync blocks andoutputting the trick play data; (e) arranging the normal play data in anormal play data region, the trick play data in a trick play dataregion, and predetermined pattern stuffing data in a stuffing region ofthe normal play data region according to a difference between apredetermined recording rate and a bit rate of the transport stream; (f)performing outer error correction on the normal play data, regardless ofthe trick play data and stuffing data among the arranged data, andoutputting error-correction-coded data; and wherein the step (f)comprises the steps of: (f1) arranging a predetermined pattern data inthe stuffing region and the trick play data region simultaneously,adding an outer parity to the normal play data, and outputtingouter-error-correction-coded data for the normal play data; (f2) addingan inner parity to the outer-error-correction-coded data, and outputtinginner-error-correction-coded data, and (g) modulating theerror-correction-coded data and transmitting modulated data to therecording medium.
 15. The method according to 14, wherein each byte ofthe predetermined pattern data is a predetermined number.
 16. The methodaccording to claim 15, wherein each number in the predetermined patterndata is the same as the other numbers in the predetermined pattern. 17.The method according to claim 16, wherein the predetermined pattern datacorresponds to arithmetic zero.
 18. The method according to claim 14,further comprising the steps of: (h) demodulating the data recorded onthe recording medium and outputting demodulated data; (i) performingerror-correction-decoding on the demodulated data; and (j) selectingerror-correction decoded normal play data during a normal play mode, andselecting error-correction decoded trick play data during a trick playmode, according to a normal/trick play mode signal, wherein the step (i)comprises the steps of: (i1) performing inner error correction decodingon the demodulated normal play data using the inner parity during thenormal play mode and outputting inner-error-correction-decoded normalplay data, and performing inner error correction decoding on thedemodulated trick play data using the inner parity during the trick playmode and outputting inner-error-correction-decoded trick play data; and(i2) arranging the predetermined pattern data used in the errorcorrection coding in the stuffing region and the trick play data region,performing outer error correction decoding on theinner-error-correction-decoded normal play data using the outer parity,and outputting outer-error-correction-decoded data.
 19. The methodaccording to claim 18, wherein in the step (i2), outer error correctiondecoding is performed by overwriting the predetermined pattern data usedduring the error correction coding in a separate error correction coderegion of the normal play data region, said separate error correctioncode region being provided as part of the normal play data region inaddition to said stuffing region and trick play data region.
 20. Amethod for recording normal play data and trick play data separately ona recording medium in a predetermined data format, and reproducing thedata recorded on the recording medium, the method comprising the stepsof: (a) adding extra information indicative of a decoding timing to areceived transport stream and outputting a transport packet to which theextra information is added; (b) mapping a first predetermined number oftransport packets, to which the extra information is added, in units ofa second predetermined number of sync blocks and outputting the normalplay data; (c) extracting trick play data from the received transportstream; (d) packetizing extracted trick play data, mapping the firstpredetermined number of transport packets of packetized trick play datain units of the second predetermined number of sync blocks andoutputting the trick play data; (e) arranging the normal play data in anormal play data region, the trick play data in a trick play dataregion, and predetermined pattern stuffing data in a stuffing region ofthe normal play data region according to a difference between apredetermined recording rate and a bit rate of the transport stream; (f)performing outer error correction on the normal play data, regardless ofthe trick play data and stuffing data among the arranged data, andoutputting error-correction-coded data; and wherein the step (f)comprises the steps of: (f1) arranging a predetermined pattern data inthe stuffing region and the trick play data region simultaneously,adding an outer parity to the normal play data, and outputtingouter-error-correction-coded data for the normal play data; and (f2)adding an inner parity to the outer-error-correction-coded data, andoutputting inner-error-correction-coded data, wherein in the step (f1),outer error correction coding is performed by overwriting thepredetermined pattern data in a separate error correction code region ofthe normal play data region, said separate error correction code regionbeing provided as part of said normal play data region in addition tosaid stuffing region and trick play data region, and (g) modulating theerror-correction-coded data and transmitting modulated data to therecording medium.
 21. The method according to claim 20, wherein eachbyte of the predetermined pattern data is a predetermined number. 22.The method according to claim 21, wherein each number in thepredetermined pattern data is the same as the other numbers in thepredetermined pattern.
 23. The method according to claim 22, wherein thepredetermined pattern data corresponds to arithmetic zero.